A conventional substrate storage container, though not shown, includes a container body for aligning and storing a plurality of sheets of semiconductor wafers vertically and a heavy lid for opening/closing an open front of the container body, and is automatically conveyed between processes as well as positioned to be loaded on a load port device attached to a processing apparatus for semiconductor wafers (see Patent Literature 1).
The container body is formed into a front open box whose front is opened for storing a semiconductor wafer of, for example, φ 300 mm or 450 mm horizontally, in which on a substantially center portion of a ceiling, a robotic flange for conveyance which is gripped to be suspended by a ceiling conveyance mechanism of a plant is attached. Further, the lid is embedded with a locking mechanism which is operated from outside by a lid opening and closing device of the load port device, and a front retainer for resiliently holding front periphery of the plurality of sheets of wafers is attached on an opposed surface opposed to the semiconductor wafer stored in the container body, thus increasing mass of the container due to these locking mechanism and front retainer.